Plant protein and collagen: can you take them together?

"Collagen protein vs plant protein" searches usually mean "can I take both." The evidence doesn't support treating a scoop of collagen as a stand-in for a scoop of plant protein, or the reverse — no trial has tested combining fava-bean-style plant protein with collagen peptides directly, and the modeling behind "collagen completes it" is a calculation about a whole diet, not a tested blend.

What the evidence doesn't support

It doesn't support a direct test of the combination: no trial we found gave people plant protein and collagen peptides together, or tested a blended product containing both, so there's no result to report on what combining them does to muscle, recovery or anything else. It doesn't support the idea that stirring collagen into a plant protein shake automatically "completes" the amino acid profile of either one — that claim rests on a modeling paper about total diet composition, not a measured effect of this specific pairing. And it doesn't support using this page to decide which one is "better" for building muscle; that's a different question, answered on its own dedicated comparison, linked below.

What the trials found

A 2019 modeling paper examined how collagen peptides fit into a person's overall dietary amino acid balance, using the PDCAAS (Protein Digestibility-Corrected Amino Acid Score) method. Collagen is missing the essential amino acid tryptophan and scores as an incomplete protein on its own. The paper calculated that collagen peptides could make up as much as roughly 36% of a person's total daily protein intake, modeled against a typical Western-pattern diet, before the diet as a whole would fall short on essential amino acids. That's a statement about total daily protein from all sources — food and supplements combined — not a test of any specific plant-protein-and-collagen combination, and it doesn't tell you what happens with two scoops of a specific product.

Separately, plant protein's own trial base is part of a broader literature comparing plant and animal protein sources generally. A 2021 systematic review and meta-analysis pooling 16 randomized trials found no significant overall difference in lean mass or strength by protein source, though animal protein had a small edge in adults under 50 specifically. That literature doesn't include collagen as a comparison arm, and no trial in it used a fava bean and fermented yeast blend specifically — it's evidence about plant protein sources broadly, read here only for context on what "plant protein" as a category is and isn't shown to do.

Questions people ask

Can I mix plant protein powder and collagen powder in the same shake?

We haven't found a trial testing that combination, and we're not aware of a documented safety concern with taking two separate dietary protein sources together. This isn't guidance on amounts or timing for a specific goal — it's an evidence gap, not a green light.

Does adding collagen make plant protein a "complete" protein?

Not automatically, and not as something this page can confirm either way. The modeling paper above is about a whole day's protein intake across many foods, not a specific plant-protein-and-collagen product. Whether any given plant protein is "complete" on its own depends on its actual amino acid profile, which varies by source and isn't always printed on the label.

Collagen protein vs plant protein: which one should I pick?

That's a different question from this page, and it's covered in more depth on our dedicated plant protein vs collagen research review, including the muscle and strength trial data for each side.

What about plant protein with collagen and creatine, or with fiber and probiotics?

We haven't found a trial testing any of those specific multi-ingredient stacks either. Combining supplements that each have their own separate research base doesn't automatically combine their effects — each ingredient's evidence still applies only to what was actually studied, at the dose that was studied.

When to talk to a doctor

Neither plant protein nor collagen is a treatment for a diagnosed muscle-wasting, connective-tissue or metabolic condition. If you have a diagnosed condition affecting muscle, joints or connective tissue, or take prescription medication, talk to a doctor before combining supplements, including these two.

Related reading: plant protein vs collagen: what the research does and doesn't show, plant protein: what the research shows, and how to choose a good plant protein.